Chemical characterization and timing of uranium occurrences in the Nonacho Basin, Northwest Territories, Canada

Abstract

The intracratonic Paleoproterozoic Nonacho Basin, deposited on the western margin of the Rae craton, Northwest Territories, Canada, contains numerous historic uranium, polymetallic and critical metal (Cu, Pb, Zn, Ni, Au, Th, Pt, Ta and Sn) occurrences near its unconformable contact with crystalline basement rocks. The integration of multiple bulk and microanalytical techniques, including petrography, scanning electron microscopy (SEM), electron probe microanalyzer (EPMA), U-Pb in uraninite geochronology using secondary ion mass spectrometry (SIMS), in addition to Re-Os in molybdenite and Ar-Ar in biotite geochronology, and inductively coupled mass spectrometry (ICP-MS) and optical emission spectroscopy (ICP-OES) has allowed for characterization of uranium occurrences within the Nonacho Basin. Developing constraints on timing, and chemical characterization of two styles of uranium mineralization: primary detrital uraninite (Hope occurrence) and a hydrothermal, remobilized mixture of uranophane±uraninite (MacInnis Lake study area) aids in understanding the metallogenic evolution of the Nonacho Basin and the western Rae craton.